This invention relates to fission reactor pumped electrical sources and, more particularly, to nuclear pumped light sources which utilize photovoltaic cells for the conversion of fission energy to electrical energy.
It is known to pump laser media using fission products produced by nuclear fission reactions. The fission products interact with an intermediate material to produce energetic particles which thereafter excite a fluid media to obtain a population inversion which produces a light output. Similarly, it is known to produce light by utilization of high energy fission products for light production.
By way of example, the following U.S. patents, incorporated herein by reference, teach various fusion and fission pumped light sources and lasers:
1. Daniel S. Pappas, "Fusion Pumped Light Source," U.S. Pat. No. 4,835,787, dated May 30, 1989, provides a long pulse high energy (14 MeV) neutron source, a fusion reactor, to generate light in a pre-selected lasing medium. The laser medium includes a first component liquid selected from Group VIII of the periodic table of the elements (i.e., a noble "gas": He, Ne, Ar, Kr, Xe, or Rn) PA1 2. Daniel S. Pappas, "Fusion Pumped Laser," U.S. Pat. No. 4,800,566, dated Jan. 24, 1989, provides a long or continuous pulse of neutrons from a Tokamak device. A conversion medium receives neutrons from the Tokamak and converts the high energy neutrons to an energy source with an intensity and energy effective to excite a pre-selected lasing medium. Such lasing medium is selected to support laser oscillations for generating output radiation. PA1 3. Walter J. Fader, "Nuclear-Pumped Uranyl Salt Laser," U.S. Pat. No. 4,160,956, dated Jul. 10, 1979, provides a UO.sub.2.sup.++ uranyl salt laser medium enriched with a .sup.235 U fission source. Fission products are produced within the uranyl salt to interact with the UO.sub.2.sup.++ ion to produce a lasing output from the uranyl salt. PA1 4. George H. Miley et al., "Direct Nuclear Pumped Laser," U.S. Pat. No. 4,091,336, dated May 23, 1978, provides a neutron source, a nuclear reactor, to irradiate a cylinder coated with .sup.235 U or .sup.10 B and containing a laser medium of Ne-N.sub.2. PA1 5. Thomas G. Miller et al., "High Power Nuclear Photon Pumped Laser," U.S. Pat. No. 4,398,294, dated Aug. 9, 1983, provides a pulsed nuclear reactor for generating neutrons to produce gamma and x-ray energy through inelastic scattering with iron. The output energy then excites Xe to generate photons which are effective to excite a laser medium of Ar, SF.sub.6, and XeF.sub.2.
The prior art fission or fusion sources are intended to produce a laser output only. These nuclear sources are intended to excite a laser medium using singly either fission fragments, fission neutrons, or fusion neutrons. The prior art does not simultaneously utilize fission fragments, fission neutrons, as well as prompt fission gamma-ray photons in concert to excite a light conversion medium. The term light conversion medium, in reference to the present invention, refers to a material which can be excited to obtain a population state inversion whereby photons are produced as the excited state decays to a lower state. The output light may be incoherent for use as a "flashlamp" or may be amplified to form a coherent, or lasing output. The production of light as both coherent and incoherent output from nuclear fission sources which utilize fission fragments only is described in M. A. Prelas et al., "Nuclear Driven Flashlamps," Lasers and Particle Beams Vol. 6, part 1. pp.26-62 (1988), incorporated herein by reference. The production of light as both coherent and incoherent output from nuclear fusion neutrons only is described in D. S. Pappas, "Physics of Fusion Pumped Lasers," Lasers and Particle Beams, Vol. 7, part 3. pp. 443-447 (1989), incorporated herein by reference. However, only a fraction of the available energy is used to generate light energy and electrical energy is not produced.
In accordance with the present invention, a fission source provides a combination of fission fragments, neutrons, and gamma rays which directly interact with a noble gas converter to obtain narrow bandwidth ultraviolet radiation. Therefore all of the fission products are utilized in the scheme herein proposed and a more efficient light source is provided.
Accordingly, it is the object of the present invention to provide a light source which can be efficient in generating electrical energy.
Another object is to convert fission energy to narrow band UV radiation.
Yet another object is to focus output UV radiation on an array of photovoltaic cells.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.